It's true that warm air rises, but it's also true that cool air sinks. I never understood why people always set top fans as exhaust, it almost always creates a negative pressure system with the CPU cooler potentially starved for air. Unless you're water cooling it's honestly always better to set them as intake. (filtered if need be)

I have a P182. I have 800rpp fans on the top and rear exhaust and 1200rpm fans on the front intakes. This produces a positive pressure in teh case and a normal convention path from front/bottom to top/rear. In the process the air flows past the HDD's, the motherboard chipset, memory and the cpu cooler (which has it's own fan).

Much depends on the case and ho constrictive the airflow is. In any case positive pressure is desirable not only for potentially better cooling, but for reducing dust intake.

Panty hose ftw..Ultra fine, lets air pass through quite well, but stops dust like crazy. I had a case with dual fans on top, over time, I actually had changed one of them to a higher pressure and the other to higher flow, the one near back acted as exhaust and the one near front as intake, yes it circled air, but I actually blocked the hole on back where there is normally an exhaust fan.

What I found was simple, my psu on bottom of case took care of itself, the fan over top of hard drive provided air to itself and graphics card, small low flow/pressure fan on side kept enough cooler air being fed to gpu what fan in front was not feeding to it, cpu cooler was push/pull east to west type with the one fan on top blowing air towards the ram/motherboard through cpu heatsink and being sucked out the top back fan, it actually kept my temps very good..Personally, I hate the cases that have fans like this, I would much rather them do away with fans on top such as they are and instead if not using a rad, have a section on front of case by optical meant fo another intake fan, this way here all the air is more or less going in straight lines.

Or better yet, all the "intake fans" are fed nice cool air from the ground which is always the coolest, this is air channeled to the fans to keep noise down and can also keep it so much cleaner with 1 maybe 2 filters this way rather then 3 or 4. It would be nice if the makers actually spent a bit of time and put some thought into this i.e noise, dust, cooling, airflow positioning, cause most cases it really is an afterthought.

I have my raven 3 now, 1 fan front a xigma 120mm CLF purple led pushing in, 2 silverstone 180mm air pen fans on bottom pushing in, psu bottom taking care of itself, 1 fan side pushing out to keep ssd and back of motherboard a bit cooler its a rough 65cfm and maybe 1.5 H2o pressure coolermaster fan, and another 120mm xigma purple led on top pulling out, the back of case I took the fan out of it(keeps my gpu 4c or so cooler then when was using a ~72cfm fan pushing in, now it just takes what it needs)

So all told 3 fans in 2 out 1 of the 2 has not to much air coming out, the one on top quite a bit.. Works very well, gpu 7870 sits around 54c gaming at 62-65% fan, cpu AMD955 OC/OV 4.17Ghz 1.44v ram 1800 range and cpu-nb/ht 2700/2070 cpu normally sits around 43c this is in a room where my hard drive normally read 34-36c :)